In contrast to the production of oil-in-water emulsions, only a limited number of emulsifying agents are available, the best of which are becoming increasingly scarce, for producing cosmetic emulsions of the water-in-oil type. Wool fat and its derivatives are still some of the most important emulsifying agents for producing creams of the water-in-oil type. However, despite their uncontested advantages, wool fat and its derivatives such as lanolin have certain disadvantages. Thus, conventional water-in-oil emulsifying agents based on wool fat and its derivatives impart a strong intrinsic odor to creams which contain them. This, in turn, requires strong perfuming which frequently cannot be tolerated by persons with sensitive skin. However, this influencing of the quality of the cream by a strong intrinsic odor is not only peculiar to wool fat and its derivatives, but also extends to lanolin-free water-in-oil emulsufying agents based on animal sterols, particularly those based on cholesterol. Furthermore, low molecular weight emulsifying agents, together with the effective substances of the cream, can be absorbed by the skin, which is not desirable in all cases.
The most widely known water-in-oil emulsifying agents for cosmetic purposes include, in addition to the said emulsifying agents based on wool, wax alcohols and sterols, and the oleic acid esters of various polyols, such as glycerine, pentaerythritol, trimethylolpropane and sorbitol. However, due to the unsaturated character of their acid component, the oleic acid esters have various disadvantages with respect to their technical use, so there there is a genuine need for new and suitable water-in-oil emulsifying agents.